Chemical contamination of the environment associated with many different types of industrial activities conducted over the last two centuries is a well documented, world-wide problem. Common environmental contaminants include several different types and forms of petroleum hydrocarbons, halogenated organic compounds including solvents (e.g., tetra- and trichloroethene, methylene chloride), pesticides (e.g., DDT and toxaphene), polychlorinated biphenyls (PCBs), and heavy metals and other inorganic contaminants such as cyanides. The available toxicological data indicates that many of these contaminants, in particular many of the halogenated organic compounds, are either carcinogenic or potentially carcinogenic to both man and animals. In addition, the available environmental and ecological data have shown that many of these contaminants tend to persist in the environment for long time periods and, consequently, they tend to accumulate in the tissues of biological organisms up the food chain. The long-term stability and extremely slow degradation of many such environmental contaminants presents a substantial, long-term hazard to human health and the environment throughout the industrialized world. Hence, there has been and continues to be a great need for improved methods for the remediation of contamination in the environment.
This invention discloses the formulation, manufacture and use of advanced solid-media chemical compositions designed and intended to enhance the biologically mediated removal ad of recalcitrant contaminants from hazardous and industrial wastes, and contaminated environmental media such as soils, sediments, sludges, surface waters, and the like. In particular, this invention provides improved means for the clean-up of contaminated sediments present in environmental settings which are difficult (if not impossible) to treat, such as the contaminated sediments present beneath streams, rivers, lakes, ponds, oceans, estuaries, bays, harbors, canals, lagoons and the like.
Many of the so-called conventional methods for the remediation or clean-up of chemically contaminated wastes, waters, soils and sediments have generally involved either the physical removal of the contaminated media or the simple mass transfer of the contaminants from one media (e.g., soil) to another (e.g., air). In general, such physical-treatment technologies do not involve the chemically and/or biologically mediated breakdown, transformation or detoxification of the contaminants. One of the most common categories of physical environmental remediation technologies for the treatment of contaminated sediments located beneath rivers, streams, lakes, and the like is dredging followed by their disposal in a landfill, which can pose a potential long-term risk to the environment. Each of the physical-treatment technologies share the same disadvantage-i.e., they do not reduce the actual amount or toxicity of the chemical contaminants, but rather they simply move the contamination from one place to another or from one media to another.
Another well-known physical treatment process which involves the thermal treatment or incineration of the contaminated materials can be an effective albeit expensive means of breaking down the molecular structure of the contaminants into non-hazardous products. For example, high-temperature incineration is known to be effective for the treatment of materials containing pesticide""s and PCBs. Thermal-treatment methods require the use of sophisticated and operation-and-maintenance-intensive equipment, the costs of which are passed on to industry in the form of expensive unit costs for soil treatment. In addition, because thermal-treatment processes are rarely, if ever, one-hundred-percent effective in the destruction of the contaminants, they can produce atmospheric emissions of contaminants or the toxic by-products of contaminants. For example, the incomplete incineration of PCBs can produce dioxins, which in turn are significantly more toxic than their xe2x80x9cparentxe2x80x9d PCB compounds.
A third category of environmental-remediation treatment technologies, bioremediation, involves the use of microorganisms to convert chemical compounds into innocuous or less harmful chemical compounds. Bioremediation technologies generally have lower costs associated with their use and implementation than do the competing physical technologies. Bioremediation technologies are also more adaptable to different types of contamination problems and variations in field conditions than are physical-treatment technologies.
The most promising bioremediation technologies provide the additional capability of treating contaminated media in-situ, i.e., in place without the need for ground-water pumping or soil excavation. Current trends in bioremediation technology indicate that the most technically feasible and commercially successful bioremediation technologies are those which utilize indigenous or xe2x80x9cnativexe2x80x9d contaminant-degrading bacteria (CDB), fungi and other microorganisms which are naturally present in the contaminated media. The presence of CDB in many different types of environments has been extensively reported in the scientific literature. There is an extensive body of prior art literature and patents concerning various means of using both aerobic and anaerobic CDB (as well as engineered or cultured bacteria) to biodegrade organic contaminants in water, soil and industrial wastes. For example, it has been reported that native Alcaligenes spp., Pseudomonas spp., and Enterobacter spp. can degrade a number of pesticides and polychlorinated biphenyls (Nadeau et al., 1994, Applied and Environmental Microbiology; Aislabie et al., 1997, New Zealand Journal of Agricultural Research; Galli et al., 1992, Pseudomonas: Molecular Biology and Biotechnology). Given the significant advantages of using native microorganisms versus the need to introduce cultured or engineered microorganisms, methods which involve the use of artificially introduced microorganisms (e.g., U.S. Pat. No. 5,932,472) are declining in favor within both the scientific and engineering communities. Recent trends in the art and literature acknowledge a growing understanding of the use of anaerobic biological processes in the treatment of many different types of contaminants that are otherwise recalcitrant under aerobic conditions. In particular, trends in the art reflect a growing understanding of the need and importance of achieving and maintaining anaerobic conditions and other factors which favor the biologically mediated reduction, biodegradation, transformation and/or detoxification of recalcitrant organic and inorganic contaminants in the environment.
The current understanding reflected by the art is that the recalcitrant nature of many halogenated organic contaminants, polynuclear aromatic hydrocarbons (PAHs), other heavy (i.e., high-molecular weight) hydrocarbons, and the like is related to the hydrophobic nature and extremely low solubilities of the contaminants. Consequently, the xe2x80x9cbioavailabilityxe2x80x9d of these contaminants, i.e., their availability to biological degradation processes mediated by microorganisms, is extremely limited under most environmental conditions. The prior art describes the use of chemical methods (e.g., Szejtli, et al., U.S. Pat. No. 5,425,881) and thermal methods (e g., Rothmel, et al., U.S. Pat. No. 5,567,324) to increase bioavailability. For a number of chemically complex hydrophobic chlorinated organic compounds, such as pesticides and PCBs, the prior art has suggested that the higher molecular weight (i.e., more chlorinated) compounds can not be practically biodegraded and thus bioremediation techniques have been all but abandoned with respect to the treatment of such compounds in the environment. For example, through laboratory and pilot-scale experiments directed at the investigation of bioremediation processes on Hudson River sediments contaminated with PCBs, General Electric (GE) researchers determined that the PCBs associated with the sediments consisted of both a labile (i.e., biologically usable) fraction and a resistant (i.e., refractory or relatively non-biologically usable) fraction (General Electric Company, 1992). The labile fraction was described by GE as the lower-molecular weight, less-chlorinated congeners that could be readily desorbed from the sediments. GE described the resistant fraction as the higher-molecular weight congeners that were adsorbed or otherwise bound to the natural organic matrix of the sediments thus greatly limiting their bioavailability to microorganisms. Inoculations with a purified PCB-degrading bacterial strain failed to improve the rate or extent of PCB reduction in the GE experiments. In addition, the GE study did not investigate any means or methods to try to increase the bioavailability of the most recalcitrant PCB congeners. Furthermore, the GE research failed to address or disclose methods or means involving the use of solid or liquid compositions to create and control optimal anaerobic conditions and Eh-pH conditions favorable to the biodegradation of the PCBs.
Alternatively, and in contrast to the present invention, further studies along the lines of GE""s prior work have all but given up on the biodegradation of the resistant PCB congeners and have instead focused on the potential reduction of the environmental risks posed by these congeners via the long-term biostabilization of these congeners in the sediments (Gan and Berthouex, 1994; Alcock et al., 1995). These studies have further suggested that PCB biodegradation continues to occur slowly over an extended time frame as different PCB congeners become ;bioavailable (Gan and Berthouex, 1994; Alcock et al., 1995).
Many compositions, means and methods have been proposed in the prior art to facilitate the bioremediation of environmental contaminants. However, few compositions, methods or means have been disclosed for the in-situ bioremediation of contamination in xe2x80x9cchallengingxe2x80x9d environments such: as contaminated sediments present beneath lagoons, lakes, rivers, streams, oceans and the like. Although a number of chemical compositions have been disclosed which are intended to promote the biodegradation of contaminants which may be present in such environments, few means or methods have been disclosed which provide these compositions in forms which can be practically, let alone reliably, applied to such environments.
U.S. Pat. No. 5,264,018 to Koenigsberg et al. (Plant Research Laboratories, Inc.) discloses a method of decontaminating soil by applying an oxygen delivery system comprised of a metal peroxide, ,fertilizer, surfactant, and metal in an amount which substantially increases the population of microorganisms in the soil that digests pollutants. The oxygen is liberated in a time-release fashion by controlling the decomposition of peroxide through xe2x80x9cintercalationxe2x80x9d with phosphate ion rather than by applying an exterior coating. The liberated oxygen can be carried to a further depth below the surface by the use of a surfactant. The composition may be applied in a liquid suspension or slurry form or as a dry application whereby oxygen release will commence once wetted. Koenigsberg et al. do not disclose the compositions of the present invention.
U.S. Pat. No. 5,849,060 to Diping et al. (Zhengzhou Centre for Popularization and Research on Zhengzhou Luxuriance) discloses a controlled-release fertilizer having water-soluble fertilizers as the nucleus and limited-soluble plant nutrient compounds as coating layers which serve to control the release rates of the fertilizer. The fertilizer is composed of nitrogen, phosphorus, potassium, magnesium, and trace elements. Diping et al. do not disclose the use of the fertilizer for uses or applications other than to promote the growth of plants, i.e., Diping et al. do not disclose the methods of the present invention, let alone any compositions or methods for the bioremediation of contaminants. Hence, Diping et al. clearly do not disclose the present invention.
U.S. Pat. No. 5,877,113 to Mehta (Organica, Inc.) discloses a solid-chemical composition for treating natural bodies of water comprising a quantity of beneficial aerobic microorganisms and a xe2x80x9cgrowth acceleratorxe2x80x9d (i.e., source of carbon and nitrogen). The components are encapsulated inside a water soluble coating or formed into microcapsules. Mehta teaches the formation of the solid composition into various shapes having a weight of at least 85 g, preferably from 170 g to 1.5 kg in order to prevent the compositions from moving with the water to which it has been added. Mehta does not discuss the use of the solid composition for the treatment of sediments. Hence, Mehta does not disclose the present invention.
U.S. Pat. No. 5,340,376 to Cunningham (The Sierra Horticultural Products Company) discloses a controlled-release nutrient composition for supplying an effective microorganism growth- and activity-promoting level of nutrients. The formulation has a core of water soluble nutrients encapsulated in a release rate-controlling coating. Cunningham teaches the use of the composition for in- and ex-situ soil treatment and aqueous applications. This patent does not disclose the use of the composition for the treatment of contaminated sediment.
U.S. Pat. No. 5,908,267 to Schuring et al. (New Jersey Institute of Technology) disclose methods for the in-situ bioremediation of contaminants whereby a pressurized gas stream is injected into the soil which then creates fracture networks in the soil into which a variety of dry, granular media can be injected and deposited throughout the soil formation to enhance in-situ subsurface soil remediation. The dry media can include nutrients, microbial inoculum, agents to generate the desired pH, buffers, time-release nutritive substances, zero valent metals, and organic compounds. Schuring et al. do not disclose the application of the dry media to environments other than the artificial fracture networks created by the use of a pressurized gas stream. In addition, Schuring et al. do not disclose compositions or methods in which the use of the dry media are dependent upon their form or density. Accordingly, Schuring et al. do not disclose the present invention.
U.S. Pat. Nos. 5,679,364 and 5,939,086 to Levy (Lee County Mosquito Control District) disclose a contaminant-reducing agent delivery composition comprised of one or more superabsorbant solid organic polymers and at least one contaminant-reducing agent (i.e., film-forming agents, microbial agents, nutrient agents, and mixtures thereof). The disclosed contaminant-reducing composition is said to be of use for the reduction of contaminants on the surface of water bodies, e.g., waterways, lakes and the like. The composition may be combined into a time-released form prepared by encapsulating, agglomerating, or formulating mixtures into solids, dusts, granules, pellets, briquets, extrusions, laminates, or into composites. The controlled release can be modified or delayed by the degree of compaction, by varying the concentration of film-forming agents, by varying the concentration of polymers, or by adding one or more binders. The composition can also be placed into water-soluble or biodegradable packets, pouches, or capsules. Levy does not disclose the use of organic and inorganic amendments other than microorganisms and microbial nutrient agents. In addition, Levy is primarily focused on the application of the compositions to contaminant spills in surface-water bodies, and goes so far as to discuss and disclose the addition of buoyancy agents to prevent sinking of the compositions. Hence, U.S. Pat. Nos. 5,679,364 and 5,939,086 to Levy do not disclose the present invention.
U.S. Pat. No. 5,700,558 to Bopp discloses a material which serves as a biodegradable absorbent for oil or other hydrocarbon liquid spills comprised of granulated foam, microbial nutrients, xe2x80x9cde-dust agents,xe2x80x9d and ground cellulosic material. Bopp also claims the formulation of the disclosed materials into a pellet form. Bopp does not disclose the application of the disclosed formulation to problems other than surface spills of contaminants, hence no means or methods are disclosed for the remediation of contaminated sediments associated with streams, rivers, lakes, lagoons or the like. In addition, Bopp does not disclose the use of inorganic amendments. Clearly, Bopp does not disclose the present invention.
U.S. Pat. Nos. 5,395,808 and 5,403,809 to Miller et al. (W.R. Grace and Co.) disclose different types of microporous bodies which are suitable for use as xe2x80x9cinorganic supportsxe2x80x9d for bioremediation catalysts and bacteria. Such porous bodies are composed of mixtures of xe2x80x9cultimate particlesxe2x80x9d comprised of bound clay, inorganic binders, extrusion or forming aids, burnout agents and forming liquids. U.S. Pat. No. 5,403,809 (Miller et al.) discloses the addition of activated charcoal and zeolite to the porous body. Spaces between the ultimate particles become the pores in the finished bodies. Uses include biotreatment of aqueous waste streams, biofiltration of gases, bioorganic synthesis of fine and commodity chemicals, absorption of liquids, and carriers for reagents. U.S. Pat. Nos. 5,395,808 and 5,403,809 to Miller et al. (W.R. Grace and Co.) do not disclose the present invention.
U.S. Pat. No. 5,397,755 to Parker et al. (W.R. Grace and Co.) discloses xe2x80x9cbioremediation support(s)xe2x80x9d for enhancing the activity of microorganisms used in the biotreatment of aqueous waste streams or contaminated vapor. The disclosed supports are low-cost, low-density siliceous glassy material, preferably pumice, used in combination with at least one material having adsorptive properties or buffering capacity. The macroporosity of the pumice allows diffusion of nutrients throughout the body and propagation of bacteria within the pores. The disclosed low-density supports are useful as xe2x80x9cfloatersxe2x80x9d for oil/organic spills on water bodies. Hence, Parker et al. clearly do not disclose the present invention.
U.S. Pat. Nos. 5,626,437 and 5,733,067 to Hunt et al. (Foremost Solutions, Inc.) disclose the use of porous walls or reactive sheets filled with porous spheres for the in-situ bioremediation of contaminated ground water and surface water. The first patent to Hunt et al. (U.S. Pat. No. 5,626,437) discloses the use of porous inorganic spheres, such as diatomaceous earth pellets, treated by inoculation with non-pathogenic microbes. The later patent (U.S. Pat. No. 5,733,067) discloses the use of reactive sheets inoculated with microbes, zero-valent metal, a leachable compound, and an adsorptive compound. No disclosures are made for the use of the support spheres for applications other than their incorporation into porous walls or reactive sheets. U.S. Pat. Nos. 5,626,437 and 5,733,067 to Hunt et al. do not disclose the present invention.
This invention discloses advanced solid-chemical compositions which are designed and intended to provide unique advantages for the anaerobic, biologically mediated removal of recalcitrant chemical contaminants from industrial wastes, soils, sediments, sludges, surface waters, and the like. Moreover, this invention provides specific advantages for the clean-up of chemical contaminants present in environments which are difficult (if not impossible) to treat using previously disclosed means or methods, including, but not limited to, streams, rivers, lakes, ponds, oceans, estuaries, bays, harbors, canals, lagoons, and the like. Contaminants which may be treated according to the means and methods of the present invention include, but are not limited to, petroleum hydrocarbon contaminants such as gasolines, fuel oils, lubricating oils, hydraulic oils, polycyclic aromatic hydrocarbons (PAHs), and the like; organochlorine pesticides such as DDT and toxaphene; arsenic and/or arsenate-based pesticides; polychldrinated biphenyls (PCBs); dioxins; halogenated organic solvents such as perchloroethylene, trichloroethylene, trichloroethane, and freon; and toxic inorganic contaminants such as cyanide, hexavalent chromium, and the oxidized forms of other toxic heavy metals. The chemical compositions of the present invention also provide significant technical advantages and cost savings when applied to the remediation of contaminated soils, ground waters, and hazardous and industrial wastes.
In the preferred embodiments of the present invention, the solid-chemical compositions are prepared, manufactured and used in the forms of pellets, tablets, caplets, capsules, briquettes, bricks, blocks, cakes, or other similar forms which enable them to sink in bodies of water and also to penetrate into the underlying sediments. The present invention also discloses solid-chemical compositions which have variable, time-dependent rates of disintegration, disaggregation, dispersal, and dissolution subsequent to their introduction to a contaminated environment. The present invention further discloses compositions which provide components which have variable, time-dependent rates of biodegradation and biological conversion in the environment so as to optimize the treatment of contaminated media which have contaminants with varying environmental half-lives, degrees of recalcitrance and/or biogeochemical reactivity.
A basic albeit further advantage of the present invention is that the preferred forms of the disclosed solid-chemical compositions which are prepared and used as pellets, tablets, caplets, capsules, briquettes, bricks, blocks, cakes, or other similar forms are easier to store, handle, and use in a wide range of environmental-remediation applications than either other forms of the compositions or chemical compositions previously disclosed in the prior art. The present invention also compliments and is ideally suited for use in conjunction with the solid-chemical compositions for bioremediation of environmental contaminants disclosed in the pending applications filed by Hince (Ser. No. 09/439,698, Nov. 15, 1999), Hince and Singer (Ser. No. 09/440,340, Nov. 15, 1999), and Hince and Singer (Ser. No. 09/441,484, Nov. 17, 1999).
A further object of the invention is to present means by which to overcome the disadvantages associated with not only the traditional means and methods of remediation previously described but the limitations of other more recent and/or technically advanced methods and means of chemical-reduction based remediation and bioremediation described in the prior art. The present invention has the further advantage that it can be used effectively either ex-situ or in-situ. The preferred embodiment of the present invention offers the further advantage of providing a means of promoting the bioremediation of contaminated sediments in-situ beneath bodies of natural water such as oceans, lakes, rivers, streams, and the like, and man-made water bodies such as waste-treatment lagoons and the like. The present invention also discloses subtle improvements in the art which provide means of treating extremely recalcitrant chemical contaminants including but not limited to PCBs, dioxins, organochlorine pesticides and their daughter products, halogenated solvents, hexavalent chromium and other inorganic contaminants present in environmental media and man-made wastes. The present invention provides for significant cost savings relative to other means and methods for environmental remediation, as it can reduce or eliminate the need for dredging, excavation, pumpage, transportation, and/or off-site treatment of contaminated sediments, wastes, soil, or water.
These and other objects and advantages of the present invention will become apparent to those skilled in the art in the following detailed description of the invention which reveals the novel solid-chemical compositions described previously, which are more particularly defined in the appended claims.